1. Field of the Invention
The present invention relates to a noise suppressor which suppresses noise transmitted through a first conductive wire and a second conductive wire.
2. Description of the Related Art
Power electronics devices such as switching power supplies, inverters, lighting circuits for lighting fixtures include a power converter circuit which converts power. The power converter circuit includes a switching circuit which converts a direct current into an alternating current with a rectangular wave. Therefore, the power converter circuit produces a ripple voltage with a frequency equivalent to the switching frequency of the switching circuit or noise associated with the switching operation of the switching circuit. The ripple voltage or noise adversely affects other devices. Therefore, it is necessary to arrange a means for reducing the ripple voltage or noise between the power converter circuit and the other devices or lines.
Moreover, recently as a communications technology used for the establishment of a home communication network, power line communications holds promise, and the development of the power line communications has been advanced. In the power line communications, a high frequency signal is superimposed on a power line to establish communication. In the power line communications, noise is produced on the power line by the operations of various electrical and electronic devices connected to the power line, and the noise causes a decline in communication quality such as an increase in error rate. Therefore, a means for reducing noise on the power line is necessary. Moreover, in the power line communications, it is necessary to prevent a communication signal on an indoor power line from being leaked to an outdoor power line.
Noise transmitted through two conductive wires includes normal mode (differential mode) noise which causes a potential difference between two conductive wires and common mode noise transmitted through two conductive wires at the same phase.
Arranging a line filter on a power supply line, a signal line or the like is effective in suppressing the noise. In Japanese Unexamined Patent Application Publication No. H10-256859, an AC line filter which removes noise on an AC power line is disclosed. The AC line filter includes a phase reversal transformer for normal mode suppression and two common mode chokes. In other words, the AC line filter includes a plurality of inductors on the same line.